Bacillus thuringiensis - an insecticide

Bacillus thuringiensis produces intracellular protein crystals (also called delta -endotoxins) which are extremely toxic to certain pests, yet cause l ittle or no harm to humans, most beneficial insects, and other non target o rganisms. After proteolytic activation in the insect's midgut, the toxin sp ecifically recognizes and binds to receptors in the insect's midgut epithel ium, forming membrane pores that disrupt the selective permeability and cau se lysis of the cells and, finally, the insect's death. Genetic engineering , including expression of B. thuringiensis genes in transgenic crop plants, offers the opportunity for further expansion of B thuringiensis bioinsecti cides. Another approach has been to incorporate B. thuringiensis genes into other micro-organisms to improve field persistence or to expand target ran ge by incorporating of several toxins into a single, cell.